Casemiro insisted Real Madrid cannot use Cristiano Ronaldo's exit as an excuse after losing their first competitive game since his £100million move to Juventus.
Atletico Madrid managed to triumph 4-2 against Real in the UEFA Super Cup on Wednesday evening, ending a run of two defeats in the last five years in European cup finals.
It was the first time the two sides had met since Ronaldo left the Santiago Bernabeu, but Casemiro would not listen to that as an explanation.
"Sure, we cannot cover things, Cristiano showed here that he has been the best in the world," Casemiro said. "But it is already past, we cannot keep thinking about him."
"We have to talk about the players we have. We want to make a stronger, more solid team, but Cristiano is already in the past."
Casemiro also took time out to back new manager Julen Lopetegui after the former Spain boss lost his first competitive game in charge of Real.
"It's still the beginning of everything," he added. "Julen is doing a great job, trying to maintain the illusion, which is not easy."
"We have won four Champions Leagues in the last five years. We have won almost everything, he is doing a great job maintaining the players' illusion of winning."
"It's still too early to talk about Julen. We cannot cover Julen's work by tonight's result."
Real begin their La Liga campaign on Sunday when they face Getafe.